1. Field of the Invention
The present invention relates to optical fiber connectors for an array of optical fibers and more particularly to multi-fiber connectors aligned with a component such as a transceiver.
2. Brief Description of Prior Developments
Due to the increasing need for higher capacity data and voice transmission, use of optical fiber arrays is becoming necessary in many applications. Optical fibers, or light guides, are utilized to transmit data encoded in the form of light i.e., electromagnetic radiation from the ultraviolet, visible-light, and infrared portions of the spectrum. The quality of data transmitted in this manner is dependent upon minimizing signal and intensity losses along the transmission path. Intensity losses in the transmitted light signal can substantially degrade the quality of the data encoded in the signal e.g., by decreasing the strength of the signal beyond the sensitivity of a light detector. In some cases, such losses can render the data unrecoverable.
Misalignment of the various junctions along the signal-transmission path is a common source of signal intensity loss. For example, misalignment between the termination point of an optical fiber and an adjacent portion of the signal path will typically produce a signal loss. Hence, a terminal for an optical fiber should position the fiber so as to allow an end of the fiber to be precisely aligned with an adjacent portion of the signal-transmission path. In particular, the signal-transmission axis of the optical fiber i.e., fiber""s longitudinal axis, should be positioned coincident with the signal-transmission axis of the adjoining portion of the signal-transmission path. While important for even single fibers, the possibility for misalignment increases when dealing with an array of fibers.
Alignment of such fiber arrays either with other arrays or with optical components can be troublesome, since the diameter of the core of these fibers is generally very small. For example, multi-mode fibers typically have a core with a diameter of about 62.5 microns. For these fibers, misalignment in any radial direction by more than about 10 microns can result in significant degradation of the optical signal being transmitted via the optical fiber. Aligning single mode fibers can be an even more difficult task since the core of typical single mode fiber is about 8 microns in diameter. Even a small degree of misalignment, e.g. 0.1 to 1 micron, for single mode fibers can result in significant degradation of the optical signal being transmitted via the optical fiber.
Maintaining precision alignment is an issue not only in the initial assembly of the receptacle portion of an optical connector, but also in the design of the receptacle to maintain alignment throughout the operating temperature range and in the presence of mechanical forces resulting from vibration, connection or pulling of the receptacle. It is important to align the various light transport elements of a receptacle assembly and it is important to align light sources and detectors to their corresponding transport means. Edge emitting lasers have previously been aligned with a laser transport element by placing an optical fiber proximate to the edge-emitting laser source, and then placing the other end of the fiber, or array of fibers as the case may be, in a ferrule which is then aligned with corresponding fibers of the laser transport element.
Vertical Cavity Surface Emitting Lasers (VCSELs) have recently emerged as a successful technology for generating encoded light signals, and for some applications have replaced edge emitting lasers. Using epitaxially-grown Bragg mirrors to form the laser cavity, the optical output of the VCSEL is emitted vertically from the surface. The VCSEL structure can lead to a host of performance advantages over conventional semiconductor lasers such as very small size for a single longitudinal mode optical output, very low power consumption, mode-hop free wavelength tunability, and two-dimensional array capabilities.
In contrast to conventional edge-emitting semiconductor lasers, the VCSEL has a radially symmetric Gaussian near-field, which enhances coupling to various optical components or fiber orientations. In addition, VCSEL technology allows the fabrication of two-dimensional laser arrays and the generation of smaller beam divergence.
It is advantageous to provide a way to actively align or couple a VCSEL, or an array of VCSELs, to an optical fiber, or array of optical fibers for inclusion into a light transport assembly. Since VCSELs are a relatively recent technology, the uses and assemblages for VCSELs have yet to be fully explored.
The invention meets the above needs by providing an improved assembly for housing actively aligned VCSELs or detectors to a light transport terminal, such as a ferrule, and a method and technique for actively aligning VCSELs and laser detectors to a light transport terminal, such as a ferrule. The method actively aligns an array of VCSELs or laser detectors to a light transport terminal, such as a first ferrule. The aligned components can then be secured to a retainer housing which can receive a plug. Then a plug, having a second ferrule with V-groove alignment portions and a substantially rectangular housing encasing the second ferrule, can be inserted into the retainer housing, thereby passively aligning the array of optical fibers carried by the second ferrule of the plug to the array of optical fibers of the first ferrule by way of posts extending from the first ferrule into the V-grooves of the second ferrule. A VCSEL or detector to optical fiber plug assembly is thus provided.
These and other features and objects of the present invention are set forth in the following description.